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Biology
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What is the role of auxin in plant phototropism?

Starting with the basics: 
1. Auxin is a plant hormone, so it is a chemical substance involved in regulating the action of certain cells within an organism.
2. Phototropism is the process by whi...

TD
Answered by Tiago D. Biology tutor
67187 Views

What is the difference between cells, tissues, organs and organ systems?

You can think of these 4 things as a hierarchy, where each 'element' is a building block for the next level. The smallest 'unit' are cells. There are trillions of cells in your body and ...

CG
Answered by Callum G. Biology tutor
79907 Views

Explain the formation of a new species

Speciation (the formation of a new species) can be broken down into a few concise steps.

The most important step is the isolation of two populations. This usually occurs because of physic...

AJ
Answered by Aidan J. Biology tutor
11961 Views

How are chloroplasts adapted to their function?

Many grana, large surface area for photosynthetic pigments, electron carriers and ATP synthase enzymes. 

Photosynthetic pigments are arranged into structures called photosystems, allows m...

MA
Answered by Matthew A. Biology tutor
113948 Views

What is the all or nothing principle?

Basically this means that if the threshold voltage of a neurone is reached -40mV, then a stimulus will be generated of always +40mV. If the threshold is not reached then there will be no signal. 

KD
Answered by Katie D. Biology tutor
9667 Views

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